Sandy Alderson couldn't believe it, couldn't believe how the game could be so cruel. The rawness of the previous 24 hours hadn't subsided. Yet, here he stood, in Citi Field, on a miserable rainy afternoon in late July, seething at what flashed across the television screen.

Justin Upton had just hit a ninth-inning go-ahead homer for the Padres, sending the Mets careening toward a wrenching 8-7 defeat July 30. It had come on the heels of a debacle.

The night before, Alderson thought he had landed the final piece in a daring in-season reboot, trading for Brewers centerfielder Carlos Gomez. The deal fell through over concerns about his hip. But first, rumors of the pact reached the playing field, right in the middle of a game. Shortstop Wilmer Flores, thinking he had been traded, was reduced to tears.

Now, a day later, Upton entered his home trot just before a downpour forced umpires to stop play. More than an hour passed before the Mets quietly made their final three outs.

With his team inching closer to wasting a season that began with so much promise, Alderson stewed in his misery as he awaited the inevitable. But as the rain fell, his frustration gave way to something else.

"In the hour and a half that ensued, it was like 'OK,' " said Alderson, who could not know the extent of the transformation that was just ahead. "I had sort of come to grips with it and I was ready to go."

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'Set the tone'

Luck resides at the center of it all, always. Winners or losers, dynasties or cellar dwellers, they are all resigned in some way to fate. There is no way to know when it will present itself. Or when it could suddenly depart. But without fail, it will happen. For the Mets, fate intervened during one of the most defining six-week stretches in the franchise's 54 years of existence.

It began with the July 31 trade deadline, the last-minute acquisition of Cuban sensation Yoenis Cespedes, and the start of a three-game sweep against the Nationals, the franchise with which they would be inextricably linked. It ended Sept. 9 with another sweep of the Nationals in Washington.

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In between, the Mets forged the identity that they brought with them Friday night against the Dodgers in Game 1 of the National League Division Series. The Mets emerged as a complete team, stronger, healthier, deeper than they had been before. Suddenly, they truly believed they could not lose.

"What we did during that period of time set the tone," Mets manager Terry Collins said. "We can do this. They could pick it up. They could rise. It's huge."

'A grind, in every sense'

Until the six weeks that shaped their season, the Mets struggled to tread water. They won 11 straight games in April, then spent the next two months frittering away the lead they had opened up.

The Nationals spent much of the first half stuck in neutral. But that alone wasn't enough to absolve the Mets, and an offense that weighed them down like an anchor.

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"It was a grind, in every sense of that word," said David Wright, who missed most of the first half with a back injury.

Travis d'Arnaud and Daniel Murphy also wound up on the DL. Its depth compromised, the Mets lineup plodded toward the deadline with overmatched backups playing every night.

On July 4, the Mets (41-41) hit the break-even mark and trailed the Nationals by 4 1/2 games, the same margin as their biggest lead in April. With the lineup sputtering, the Mets hesitated to promote top prospect Michael Conforto, for fear that pressure to be a savior might be overwhelming.

"Pitching, there was absolutely no question that they kept us float," Cuddyer said.

Indeed, somehow, the Mets kept themselves within arm's reach.

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One club official put it bluntly: "It's a [expletive] miracle."

Alderson got to work. In the days leading up to the deadline, he traded for veterans Kelly Johnson and Juan Uribe. He added reliever Tyler Clippard.

After a trade for the Brewers' Gerardo Parra fell through, the Mets acquiesced and promoted Conforto.

Wright, d'Arnaud and Murphy would eventually return to the lineup, providing another boost. But on that rainy Thursday afternoon July 30, one day before the deadline, the Mets still searched for one more big bat to put themselves over the top. To do so, the front office would have to show the agility to quickly turn the page on the Gomez trade falling through.

"When you finish a deal like the Gomez trade, you take a deep breath and say 'we got it done,' " Alderson said. "And then suddenly, you've got to start over again. And the next day, we lose that game."

'I followed my boss' orders'

Alderson called the loss "devastating." Indeed, some members of the organization left Citi Field that afternoon feeling physically ill. With the hours dwindling, the Mets still had no idea what it would take to land Cespedes.

Not until the day before did the Mets even know that the Tigers slugger was on the market. Word came via a phone call from one of Collins' mentors.

Jim Leyland, the former manager was working as an assistant with then-Tigers GM Dave Dombrowski, who suggested he reach out to his old friend.

"Maybe a call to Terry would help, just tell him about Cespedes," Leyland said of Dombrowski's instructions. "So I followed my boss' orders."

The Mets initially held concerns about Cespedes' ability to play centerfield, a key element of the deal. But by Friday morning, they talked themselves out of that barrier. At around 3:45 p.m., with just 15 minutes to spare, the Mets got their big bat.

Jubilation swept the organization's tortured fan base. But within the executive suite at Citi Field, there were no fist pumps or fireworks. Alderson's years in baseball had taught him not to jump the gun.

"You never know if it's going to work out," Alderson said. "But to expect that he would have had the six-week performance that he had would have been unrealistic."

'A changed set of expectations'

Tim Teufel, the Mets' current link to the 1986 championship team, rose to speak. He remembered the way New York buzzed when the Mets ruled the baseball world. He wanted that feeling again. On July 31, that vision became a reality.

In five years as Mets manager, most of them spent squeezing whatever he could out of a losing team, Collins had never seen Citi Field come alive as it did when the Nationals came to town with a three-game lead.

"We knew this series against them in our park was a defining moment," Collins said. "Either we were going to be way behind or we were going to keep our heads above water. We kept our heads above the water."

Flores, his tearful outburst still fresh, set the tone with the biggest swing of his life. After Matt Harvey dominated the Nationals, Flroes' walk-off homer in the 12th inning gave the Mets a 2-1 lead and cut their deficit to two games.

"It kind of unfolded slowly," Alderson said. "It was a low-scoring game. But when Flores hit the home run, it was kickoff."

The next night, Lucas Duda hit a pair of homers and Jascob deGrom held the Nationals to two runs in a 3-2 victory. The lead was down to one. In the finale, Noah Syndergaard held the Nationals to two runs in eight innings, giving the Mets a 5-2 victory. They had pulled even in the NL East.

"Those three games became the best evidence for a changed set of expectations," Alderson said.

Syndergaard, the fireballing rookie, called the start his most important of the season.

"It was a great atmosphere there," he said. "It was a huge series, so I felt like that was when I made the jump into becoming a big-league pitcher."

Syndergaard wasn't the only one to believe that something had changed after the sweep.

"It gave us that final step of confidence," Cuddyer said. "I think we were a confident group and we believed in ourselves out of spring training. I think what that did was take our confidence to another level, which helped us then go into Washington and sweep them."

'This could be destiny'

By the time the Mets arrived at Nationals Park for the start of a three-game series against the Nationals, they had vaulted to a three-game lead. Cespedes entered a historic tear. The rest of the lineup followed suit. The time had arrived to seize control of their own fate.

"I remember thinking before the series in Washington that in the worst case, we're a game up when we leave here. Best case, we're seven up," Alderson said. "And I don't think any of us really expected that we'd be seven up."

The Mets defied every expectation. Three times they fell behind the Nationals. Three times they rallied to win in improbable fashion. The lead had grown to seven games.

"That's when I knew that this could be destiny," said J.P. Ricciardi, the Mets' special assistant to the GM.

Nationals reliever Drew Storen broke his hand after allowing Cespedes' clutch homer in the second game of the series, personifying a clubhouse that would ultimately decay. Nationals manager Matt Williams would be fired, the scapegoat for a season gone wrong.

Like strands of DNA, the Mets and Nationals had become intertwined. But the Mets personally delivered the coup de grace on their way to the National League East title.

Said Alderson: "When we left there, we went to Atlanta and it was almost like we couldn't lose."

In the six-week period starting July 31, the Mets went 26-11. Their once-moribund offense averaged more than six runs per game. Cespedes hit .310 with a stunning 14 homers in that span.

After four years of painful rebuilding, the Mets clinched Sept. 25 in Cincinnati. And on the eve of the Mets' first playoff series since 2006, the difference was noticeable.

"Definitely a completely different team," Dodgers' Game 1 starter Clayton Kershaw said. "Obviously, a lot better than what we faced in July."

Through an ability to react swiftly at the trade deadline, the Mets had transformed their identity. But as the days leading up to that critical six weeks had proven, there was another reason.

"There's always some luck involved," Alderson said. "Any success you have, there's a fair amount of luck involved. We readily admit that."